Bluetooth is an open standard specification for radio frequency-based, short-range connectivity. Bluetooth is designed to be an inexpensive, wireless networking system for a variety of devices (i.e., “terminals”) such as mobile telephones, keyboards, mice, displays, etc. Bluetooth terminals that are within transmission range of one another (typically, 10 meters) form small ad-hoc networks called piconets and networks of multiple piconets called scatternets.
FIG. 1 depicts wireless telecommunications system 100 which communicates via Bluetooth. Wireless telecommunications system 100 is a Bluetooth piconet that comprises five terminals: Bluetooth-enabled personal wireless terminal 102-1 (e.g., a mobile telephone, a personal digital assistant [PDA], etc.) carried by user 101-1, Bluetooth-enabled personal wireless terminal 102-2 carried by user 101-2, Bluetooth-enabled computer keyboard 103, Bluetooth-enabled computer mouse 104, and Bluetooth-enabled desktop computer 105.
Users 101-1 and 101-2 can move about and can enter commands into personal wireless terminals 102-1 and 102-2, respectively, via one or more input mechanisms (e.g., keypad input, pen-based input, voice input, etc.). Personal wireless terminals 102-1 and 102-2 also typically have one or more output transducers (e.g., liquid-crystal display, speaker, etc.) to present content (e.g., a web page, an audio clip, output of an executed query, etc.) to users 101-1 and 101-2, respectively.
Examples of commands for personal wireless terminals 102-1 and 102-2 include: adjusting speaker volume; editing information in a spreadsheet; entering a move in a Chess game; starting a sound clip; capturing an image with a digital camera embedded in the wireless terminal; capturing an acoustic signal with a microphone embedded in the wireless terminal; downloading a web page; issuing a query that searches a database stored on a server; sending an email message; and placing a telephone call.
Some computing devices such as wireless terminals, desktop personal computers (PCs), and servers require a user to log in to the device before allowing the user to use the device. For example, when a personal computer (PC) that runs on the Windows XP or Linux operating system is powered on, the user is confronted with a log-in screen that asks for the user's username (also referred to as a screen name for Internet service providers such as AOL) and password. The user is can not proceed past the start-up screen until he or she provides a valid username and password combination.
Some computing devices provide, in addition to a log-in screen, one or more authorization mechanisms to restrict access to data, commands, or both. For example, PCs that run on the Windows XP or Linux operating system enable a data file to be associated with a particular user or group of users, thereby allowing only the associated user(s) to access the data file. In some authorization mechanisms, separate read- and write-permissions can be associated with a data file, thereby partitioning users into four categories: (i) those who can read and write to the data file, (ii) those who can read the data file but cannot write to it, (iii) those who can write to the data file but cannot read it, and (iv) those who can neither read nor write to the data file. Furthermore, some authorization mechanisms enable a command (such as an executable file) to be associated with a particular user or group of users, thereby allowing only the associated user(s) to execute the command.
The mechanism for restricting who can read, write, and execute a file is a great advantage in many practical situations, but it does not provide the flexibility and appropriateness necessary for many other situations. Therefore, the need exists for innovative restriction mechanisms.